The type of packaging means, which is most widely used at the present time for transporting liquids, in particular milk and fruit juices, is a parallelepipedic packaging means or carton which comprises a tubular member of carrier or backing material which is coated on both sides with plastics material and which is closed at its ends in the region of the end walls thereof by transverse closure ribs, being made into a parallelepipedic shape, so that at each end wall there are two oppositely disposed double-walled triangular flaps which initially project outwardly from the end walls of the packaging means and which are finally folded over to lie against adjacent side walls or the end walls of the package.
Many packaging means of that kind are also used for filling material in powder or grain form. In some known packaging means, the pouring opening is formed by perforated lines or other weakened lines being punched or stamped in the outer layer or ply of the packaging means, the packaging means being torn off along the perforated or weakened line after the corresponding triangular flap has been folded out into the open position.
Also known is an arrangement comprising an opening which is already punched out of the material forming the packaging means and which is fluid-tightly covered over by a strip portion. The cover strip portion is gripped and pulled up by means of a free gripping portion which is not secured to the side wall of the packaging means, thus exposing the tear-open opening, in the form of a round or elongate hole, which is disposed on the inside of the triangular flap. A disadvantage with that known arrangement is that the material is not poured out of the packaging means in the desired form of a jet or stream, in order to avoid spilling the material.
In another kind of packaging means, the attempt has been made to provide a square or rectangular slot to act as the pouring opening, the slot being covered by a closure strip portion and being disposed on one side of the end wall, beside the transverse sealing seam. However, sealing a cover strip portion quite generally involves problems, on the one hand in regard to producing a satisfactory seal and on the other hand in regard to making it easy for the cover strip portion to be torn off. Similar problems also arise when the pouring opening, which is first punched out and then closed off by the cover strip portion, is disposed in the upper wall of the triangular flap portion. Therefore, various different opening arrangements have been developed, solely in the art of parallelepipedic packaging means, wherein the transverse sealing seam which closes off the end wall is itself undone over a certain distance, or in which use is made of tearing aids, such as for example threads or cords which are welded into the arrangement.
Particularly since the increase in cost of crude oil, the manufacturers of packaging means for containing fluids are faced with the requirement of using a minimum amount of plastics material, in particular as a coating for the carrier material, and making the machine for producing the packaging means as simple as possible, as far as possible without using a cover strip portion which has to be separately sealed in position from the interior and possibly even from the exterior. In that connection, compromises had repeatedly to be accepted as between the ease of opening the packaging means, on the one hand, and a satisfactory sealing means on the other hand.
In comparison with that, West German Laid-Open Patent Application No. 22 10 013, published Sept. 6, 1973, discloses a packaging means for fluids, wherein the side walls also comprise cardboard which is coated with thermoplastic material, whereas the top and the bottom comprise thermoplastic material without a carrier material. When in a condition of readiness for filling, that packaging means is of such a configuration that the top is joined to the side walls by an injection process along the four edges of the top, whereas, for the purposes of filing the packaging means, the bottom is joined to the side walls by an injection process, only along one edge. Such a packaging means is inexpensive to produce, practical in design and reliable in use. In a similar way to the known parallelepipedic packaging means for liquids, which are most widely used, that known packaging means is also of an exact shape, with a high degree of stability and rigidity and with the possibility of shrink wrapping, for combined bundles.
The packaging means which is disclosed in the above-indicated publication is so-to-speak stood on its head for filling purposes; for the top which is made in one piece with the opening means is first positioned at the bottom, while the bottom which is joined to the side walls only along its one side edge, together with the open tube portion therebeside, is positioned upwardly. When producing such an opening means, there is no longer any need for complicated injection moulds for injection moulding the thermoplastic end walls in position on the side walls, and the tools may be easily pulled or pushed out of the tube portion.
After being filled, the known packaging means is closed at what subsequently forms its bottom. In that operation, difficulties may also arise in regard to centering the arrangement and producing a precisely fluid-tight weld, or at least the apparatus expenditure involved in closing the end wall which forms the bottom of the package is not inconsiderable, although the main centering work is already done by virtue of the bottom of the packaging means being secured to a side wall by the injection process.